(20 U.S.C. 6301 et. seq.), as amended by this Act, from programs. authorized under the Elementary and Secondary Education Act. of 1965 (20 U.S.C. 6301 et seq.), as in effect on the day before. the date of enactment of this Act.
The efficacy of a vaccine is different from its effectiveness. It is dependent on several factors such as: 1  adherence to vaccine schedules. 2  the disease â some diseases have vaccines against them that perform better than for other diseases. 3  the strain of vaccine â some vaccine strains are more effective than others.
Although vaccines are not 100% effective and can become less effective if the virus mutates, they still offer some protection. Current flu vaccines last for about a year and give about 70-80% protection against infection with strains of influenza virus that are very similar to those used to make the vaccine.It is too early to predict how the swine flu virus might mutate.lthough vaccines are not 100% effective and can become less effective if the virus mutates, they still offer some protection. Current flu vaccines last for about a year and give about 70-80% protection against infection with strains of influenza virus that are very similar to those used to make the vaccine.